docs: def plot_compare(self, lD, key=None,
                       cmap=None, ms=4, vmin=None, vmax=None,
                       vmin_map=None, vmax_map=None, cmap_map=None, normt_map=False,
                       ntMax=None, nchMax=None, nlbdMax=3,
                       lls=None, lct=None, lcch=None, lclbd=None, cbck=None,
                       inct=[1,10], incX=[1,5], inclbd=[1,10],
                       fmt_t='06.3f', fmt_X='01.0f', fmt_l='07.3f',
                       invert=True, Lplot='In', dmarker=None,
                       sharey=True, sharelamb=True,
                       Bck=True, fs=None, dmargin=None, wintit=None, tit=None,
                       fontsize=None, labelpad=None, draw=True, connect=True):
          """ Plot several Data instances of the same diag
  
          Useful to compare :
                  - the diag data for 2 different shots
                  - experimental vs synthetic data for the same shot
  
          """
          C0 = isinstance(lD,list)
          C0 = C0 and all([issubclass(dd.__class__,DataAbstract) for dd in lD])
          C1 = issubclass(lD.__class__,DataAbstract)
          assert C0 or C1, 'Provided first arg. must be a tf.data.DataAbstract or list !'
          lD = [lD] if C1 else lD
          kh = _plot.Data_plot([self]+lD, key=key, indref=0,
                               cmap=cmap, ms=ms, vmin=vmin, vmax=vmax,
                               vmin_map=vmin_map, vmax_map=vmax_map,
                               cmap_map=cmap_map, normt_map=normt_map,
                               ntMax=ntMax, nchMax=nchMax, nlbdMax=nlbdMax,
                               lls=lls, lct=lct, lcch=lcch, lclbd=lclbd, cbck=cbck,
                               inct=inct, incX=incX, inclbd=inclbd,
                               fmt_t=fmt_t, fmt_X=fmt_X, fmt_l=fmt_l, Lplot=Lplot,
                               invert=invert, dmarker=dmarker, Bck=Bck,
                               sharey=sharey, sharelamb=sharelamb,
                               fs=fs, dmargin=dmargin, wintit=wintit, tit=tit,
                               fontsize=fontsize, labelpad=labelpad,
                               draw=draw, connect=connect)
          return kh